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<title>GNU gprof: Call Graph</title>

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<a name="Call-Graph"></a>
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<a name="The-Call-Graph"></a>
<h3 class="section">5.2 The Call Graph</h3>
<a name="index-call-graph"></a>

<p>The <em>call graph</em> shows how much time was spent in each function
and its children.  From this information, you can find functions that,
while they themselves may not have used much time, called other
functions that did use unusual amounts of time.
</p>
<p>Here is a sample call from a small program.  This call came from the
same <code>gprof</code> run as the flat profile example in the previous
section.
</p>
<div class="smallexample">
<pre class="smallexample">granularity: each sample hit covers 2 byte(s) for 20.00% of 0.05 seconds

index % time    self  children    called     name
                                                 &lt;spontaneous&gt;
[1]    100.0    0.00    0.05                 start [1]
                0.00    0.05       1/1           main [2]
                0.00    0.00       1/2           on_exit [28]
                0.00    0.00       1/1           exit [59]
-----------------------------------------------
                0.00    0.05       1/1           start [1]
[2]    100.0    0.00    0.05       1         main [2]
                0.00    0.05       1/1           report [3]
-----------------------------------------------
                0.00    0.05       1/1           main [2]
[3]    100.0    0.00    0.05       1         report [3]
                0.00    0.03       8/8           timelocal [6]
                0.00    0.01       1/1           print [9]
                0.00    0.01       9/9           fgets [12]
                0.00    0.00      12/34          strncmp &lt;cycle 1&gt; [40]
                0.00    0.00       8/8           lookup [20]
                0.00    0.00       1/1           fopen [21]
                0.00    0.00       8/8           chewtime [24]
                0.00    0.00       8/16          skipspace [44]
-----------------------------------------------
[4]     59.8    0.01        0.02       8+472     &lt;cycle 2 as a whole&gt; [4]
                0.01        0.02     244+260         offtime &lt;cycle 2&gt; [7]
                0.00        0.00     236+1           tzset &lt;cycle 2&gt; [26]
-----------------------------------------------
</pre></div>

<p>The lines full of dashes divide this table into <em>entries</em>, one for each
function.  Each entry has one or more lines.
</p>
<p>In each entry, the primary line is the one that starts with an index number
in square brackets.  The end of this line says which function the entry is
for.  The preceding lines in the entry describe the callers of this
function and the following lines describe its subroutines (also called
<em>children</em> when we speak of the call graph).
</p>
<p>The entries are sorted by time spent in the function and its subroutines.
</p>
<p>The internal profiling function <code>mcount</code> (see <a href="Flat-Profile.html#Flat-Profile">The
Flat Profile</a>) is never mentioned in the call graph.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="Primary.html#Primary" accesskey="1">Primary</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Details of the primary line&rsquo;s contents.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Callers.html#Callers" accesskey="2">Callers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Details of caller-lines&rsquo; contents.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Subroutines.html#Subroutines" accesskey="3">Subroutines</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Details of subroutine-lines&rsquo; contents.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Cycles.html#Cycles" accesskey="4">Cycles</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">When there are cycles of recursion,
                   such as <code>a</code> calls <code>b</code> calls <code>a</code>&hellip;
</td></tr>
</table>

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